Experience with explosive hardening of railway frogs from hadfield steel

Abstract

A railway turnout is a special construction allowing a ride of a railway vehicle in a given direction. A part of each turnout is a frog (alternatively - crossing), it allows to cross rails and a definitive tracks separation of two different directions. The most suitable material for a production of extremely stressed railway turnouts frogs is austenitic highly alloyed manganese steel - Hadfield steel. This steel, with chemical composition of carbon (1,2%), mangan (12%), silicon (0,45%) and austenitic structure, is able to harden its working surface (i.e. to increase its surface hardness) under a sufficient pressure and shock loading because of railway wheels shocks during the train passage through the turnout. But the hardening of Mn frog running surfaces can be done before its inserting into the track using a special technology - explosive hardening. This special Mn frogs hardening technology uses world's leading manufacturers of railway turnouts. DT-Výhybkárna a strojírna, company registers recently great interest, especially from foreign customers, in railway turnouts contain Mn frogs with explosive hardened running surfaces. Foreign customers requirements vary depending on internal regulations, standards and norms of the country where the turnout will be installed. This article shows Hadfield steel explosive hardening tests, which had to be made because of fulfillment with requirements of existing and future explosive hardened Mn frogs customers.